Method and apparatus for generating electricity from the flow of fluid through a well

ABSTRACT

A method and apparatus for generating electricity from a generator driven by the flow of fluid flowing from a fluid producing well. A fluid driven motor is positioned in the pipeline adjacent to or above the well head such that the fluid passes through the motor to turn the motor shaft to drive the generator. By controlling the electrical load connected to the generator, the force required to drive the motor and thereby the pressure reduction across the motor can be controlled. The electricity produced by the generator may be used to heat the fluid in the pipe to prevent freezing of the fluid. The electricity can be utilized to heat the emulsion in an emulsion separator dehydrator for separating gas, water, and oil prior to its introduction into the pipeline. Separate motor may be utilized for gaseous fluid and liquids. Where the well produces both gas and liquid a separator is employed to separate the gas and liquid.

BACKGROUND

Fluid pressure at the well head generally ranges from 200 to 5000 poundsper square inch and is generally reduced to a pressure of 1000 poundsper square inch or less by delivering the fluid through a choke beforethe fluid enters a pipe line to a storage tank. A typical chokecomprises a flow passage with a fixed diameter or one in which the flowpassage may be varied by turning a valve. Significant refrigeration orcooling of the fluid occurs when the fluid at 5000 pounds per squareinch passes through an orifice in the choke and expands into the line at1000 pounds per square inch. The resultant refrigeration causesformation of frost on the surface of the pipe line and may result infreezing the fluid within the pipe line thereby blocking the passage ofthe fluid through the line.

Heretofore, heaters have been employed to transfer heat to the fluidwhich is passed through the choke. Heretofore, a portion of the gas oroil produced by the well has been burned to heat air in a heat exchangerformed around the choke or pipe line.

Burning of fuel gas or oil from the well for heating fluid produced bythe well in some instances results in consumption of significantpercentages of the fuel produced by the well. It is often necessary toprovide a source of gas, for example butane, for heating liquid toseparate water from oil if an insignificant volume of gas is produced bythe well to provide the required heat. This results in waste of thatportion of gas which is burned to heat the pipe line or results in acostly expenditure to provide other hydrocarbon type fuels for heatingthe liquid for separation of the fluid produced or for heating toprevent freezing.

Wells generally produce an emulsion of oil, gas and water and variousother liquids which are very corrosive in nature. Before introduction ofthe fluid into the pipe line, it is desirable to separate the gas andwater from the oil. An emulsion separator is often used comprising aholding tank. The emulsion is delivered into the upper portion of thetank and a heater is positioned below the tank to heat the emulsion. Theheat causes the gas to boil off and the gas is piped off at the top.Warm oil will float to the top while the water goes to the bottom. Theoil is syphoned off and the water is drained off of the bottom.Heretofore these devices have utilized gas or oil burners which haveconsumed a portion of the gas or oil from the well or must besupplemented with butane and, therefore, consumes more of the fuel beingproduced.

SUMMARY

I have devised a process and apparatus for generating electricity toreduce the pressure of fluid flowing from the well head to the pipe lineand to use the electricity to heat the pipe line and separate theemulsion into gas, water, and oil. The apparatus utilizes the energyheretofore lost when using a conventional choke to reduce pressureadjacent the well head.

In a typical oil or gas well, a well head is positioned above the casingto control the flow of fluid from the well. A motor is positioned withinthe casing or downstream from the well head such that the fluid flowsthrough the motor to drive the motor and turn the output shaft. Theoutput shaft is connected to a gear reduction transmission which isdrivingly connected to a generator. After the fluid passes through themotor, it passes into a pipe line to be connected with other wells fortransfer to a storage facility.

In wells which produce both liquid and gas, a separator such as a gasseparator inducer is placed in the casing of the well or downstream fromthe well head to preliminarily separate the liquid and gas. The liquidpasses through a liquid driven motor. The gas is diverted through a gasdriven turbine or a positive fluid driven motor which drives a separategenerator.

The power required to drive the generator is directly proportional tothe electrical load connected to the generator such that a larger loadon the generator requires more power to drive the generator. Therefore,by controlling the electrical load by a series of heaters and resistorsconnected to the generator, the power required to drive the generatorcan be controlled and, therefore, the pressure reduction across themotor can be controlled. In most wells the fluid pressure needs to bereduced and it is desirable to utilize the energy given up by the fluidin reducing the pressure in a useful manner.

The electrical power generated by the generator can be utilized to heatthe pipe line or choke to prevent freezing of the pipe line in coldweather. In case of a low pressure well, electricity generated by fluidflowing from another well may be used to pump fluid from the lowpressure well through the pipe line to increase the pressure to adesired line pressure.

In addition, the electricity is used to power electric heating units,such as Calrods, in an emulsion separator treatment tower whichseparates the gas, oil, and water.

The primary object of the invention is to utilize the energy of the highpressure fluid flowing from a well in a useful manner to reduce wastefulconsumption of hydrocarbon fuels or loss of energy at the well site.

Another object of the invention is to produce electricity which may beutilized in transferring heat to the fluid in the pipe line to maintainthe flow of fluid in the pipe line.

A still further object of the invention is to produce electricity at thewell head of a high pressure well which may be utilized to increase theflow of fluid through a pipe line from a lower pressure well.

A still further object of the invention is to provide electricity whichmay be utilized to produce heat in an emulsion separator tower in placeof burning hydrocarbon fuels.

A still further object of the invention is to control the pressurereduction adjacent the well head in a manner which will not result infreezing liquid in the pipe line by forcing the fluid to flow across aloaded motor or turbine.

Other and further objects of the invention will become apparent uponreading the detailed description hereinafter following and studying thedrawings annexed hereto.

DESCRIPTION OF THE DRAWINGS

Drawings of a preferred embodiment of the invention are annexed hereto,so that the invention may be better and more fully understood, in which:

FIG. 1 is a diagrammatic view of a separator in a well with a fluiddriven motor and gas driven turbine;

FIG. 2 is an enlarged side elevational view illustrating the fluiddriven motor -- generator, parts being broken away to more clearlyillustrate the details of construction, with diagrammatic wiringconnections, said view taken along line 2--2 of FIG. 1;

FIG. 3 is a cross-sectional view taken along line 3--3 of FIG. 2;

FIG. 4 is an enlarged side elevational view of the gas driven turbinetaken along line 4--4 of FIG. 1 in association with a second well and anemulsion separator;

FIG. 5 is a cross-sectional view taken along line 5--5 of FIG. 4 whichis enlarged to more clearly illustrate the details of construction;

FIG. 6 is a perspective view of an emulsion separator, parts beingbroken away to more clearly illustrate the details of construction; and

FIG. 7 is a plan view taken along line 7--7 of FIG. 2.

DESCRIPTION OF A PREFERRED EMBODIMENT

Referring to FIG. 1 of the drawing, the electrical generator devices 6and 8 are positioned on a well head 10. The well head 10 is secured tothe well casing 12 which has a tubing string 14 to form an annulus 13.Tubing 14 is connected to the oil generator device 8 and the annulus 13communicates with pipe 15 which communicates with the gas generatordevice 6.

Means to separate the fluid and gaseous substances is positioned in thewell casing 12. This device can be positioned at any position along thelength of the well casing 12 or as illustrated at the surface S as shownin FIG. 1 of the drawing. The means to separate gas and liquid comprisevarious configurations, one such device is an electrically drivenseparator manufactured by FMC and designated Model SO-C GasSeparator/Inducer. The fluid gas separator 17 is positioned on thetubing 14 just above a seal unit 19 and utilizes basic centrifugalforces to separate the gas from the liquid. The liquid moves outwardlyand is diverted to the center tubing 14 which communicates with tubing14a to the oil generator device 8. The gas remains in the center and isdiverted into the annulus 13 which communicates with pipe 15 and whichis connected to the gas generator device 6. The pressure within the wellmay be between 200 and 5000 psi. The pump may be necessary to lift theliquid the remaining distance.

Suitable support means 21 is provided above well head 10 to support thegenerating devices 6 and 8. As best illustrated in FIGS. 1 and 2, thegenerating device 8 for the oil fluid generally comprises a fluid drivenpaddle type generator motor 24 and a device for the generation ofelectricity from the gaseous substances generally comprises a turbinemotor 224.

As best illustrated in FIGS. 1, 2, and 3, generator 8 is secured abovethe well head 10 which is bolted to a pipe adaptor 18 by bolts 20 whichsecure flange 10a of well head 10 and flange 18a of adaptor 18 together.A flow control valve 22 is secured at one end to the upper flange 18b ofadaptor 18 to control the flow of fluid upward from the well. The motor24 is secured by support bracket 26 to the well platform andcommunicates with the well by elbow 28 secured between valve 22 andmotor housing 30.

Motor 24 may be of any type of fluid driven motor, such as the oneillustrated in FIG. 2, showing a rotary paddle type motor comprisingimpellors 32 and 34 which are secured to shafts 36 and 38. Impellor 32on shaft 36 rotates gear 40 which drives gear 42 on drive shaft 38.Drive shaft 38 is journalled through seal 44 at one end of the motorshroud 48.

Inlet flange 50 communicates with elbow 28. Fluid passes through elbow28 to housing 30 and rotates impellors 32 and 34, and passes throughexhaust shroud 52 into elbow 54.

Drive shaft 38 is connected to a gear reduction transmission 56 which isbolted and secured to support means 21 by bracket 58. Transmission 56has an output shaft 60 which is connected to a generator 62.

Depending upon the desired type of current needed, generator 62 can beused to produce alternating or direct current. Generator 62 is bolted orotherwise secured to support bracket 58 to maintain alignment of theshafts 38 and 60. Generator 62 has output lines 64 and 66 to conduct theelectrical current.

Adaptor 68 is bolted or otherwise secured to an electric heating element70 which comprises an electric heating element wound about the pipe coreto heat the fluid as it passes through that section of the pipe. Choke72 comprising a variable type choke having a handle 74 for adjustingflow therethrough is secured in the pipe line between heater 70 and pipeline 76. A pump 78, diagrammatically illustrated in FIG. 1, is drivinglyconnected to an electric motor 80. Pump 78 pumps fluid into pipe line82.

As best illustrated in FIGS. 4 and 5, the gas generating device 6comprises a turbine shroud 230. Shroud 230 is T-shaped having an outlet255 with communicates with pipe 15 and well head 10.

The turbine shaft 238 is journalled through support means such as rollerthrust bearings 98 and 100 secured in bearing supports 102 and 104.Bearing support 104 has hollow passages formed therethrough to allow theflow of fluid through the support 104. Turbine shaft 238 has bearingshoulders 106 and 108 formed thereon to limit longitudinal movement ofthe turbine shaft 238. End cap 244 has seals 244a to seal about shaft238.

The turbine blades 232 are secured to the end of shaft 238 in turbineshroud 268 which is bolted or otherwise secured to housing 230. Fluidpasses from the well casing annulus 13 into the well head 10, pipe 15and shroud 230 and passes through the bearing support 104, and blades232 to turn shaft 238.

As illustrated in FIG. 4, shaft 238 is connected to transmission 256which is drivingly connected to generator 262 by shaft 260 as previouslydescribed. The output terminals of generator 262 are connected to lines264 and 266. Lines 264 is connected to rheostat 288 to control thecurrent to heater 270.

As best illustrated in FIG. 5, heater 270 comprises a shield 271a ofnon-conductor material which surrounds heater element 271b. Heaterelement 271b is wrapped around the core element 271c. Conductors 284 and286 are connected in parallel to conductors 264 and 266 to providecurrent to heat 270. A second heater 271 may be connected to lines 264and 266 on a second well as illustrated in FIG. 3. The well may be inthe adjacent vicinity or further away. Heater 271 is wrapped about achoke 272 having a control handle 274 to control the flow of fluid fromthe second well casing 12' into outlet line 276. Connector means 110connects the output line 112 from turbine motor 224 to output line 276of the second well.

Several wells are generally connected together on a common pipe line toreduce the number of pipe lines which are laid to carry the fluid tostorage tank. Once the desired pressure has been determined on the pipeline, it is necessary to adjust each well to produce that pressure tomaintain flow through the pipe line. For instance, the pipe linepressure may be established at 1000 psi and the well may be producing5000 psi. It would be necessary to reduce the well pressure of 5000 psidown to 1000 psi to control the pipe line pressure.

The force necessary to rotate generator 62 to produce electricity iscontrolled by a load across conductors 64 and 66. The force is adjustedby controlling the electrical load on the generator. A heater 70 isconnected by conductor 84 to line 66 and by conductor 86 through arheostat 88 to line 64. Rheostat 88 controls the amount of electricitywhich passes through heater 70 to control the load on generator 62.Further a rheostat 90 is positioned in a series in line 66 to furthercontrol the load on generator 62. A motor speed control, such asrheostat 92 is connected in series between line 64 and first input ofmotor 80 by line 94. The ground of motor 80 is connected by line 96 toline 66. When necessary to increase the pressure of fluid flowing intoline 82, pump 78 motor 80 is actuated. The speed of motor 80 iscontrolled by rheostat 92. Line 66 and 64 may be connected to otherelectrical devices such as lights at the well head or at other wellswhich do not produce enough fluid pressure to allow generation ofelectricity by the method hereinbefore described.

By controlling the load on generator 62, the power requirements to drivegenerator 62 are controlled. Motor 24 will reduce the pressure from theinlet 50 to the outlet 52 which is directly proportional to the powerrequirements of generator 62. Therefore, by controlling the load ongenerator 62, the pressure drop from the inlet 50 to the outlet 52 maybe controlled. On cold days, heater 70 is utilized to constitute aportion of or all the load on generator 62 to control pressure droppedacross motor 24 thus causing less refrigeration as the fluid flowsthrough choke 72.

Output line 282 is connected to a means to separate the fluid such asemulsion separator tower 114. Lines 116 and 118 are connected across theoutput terminals of generator 262 to provide a means to heat theseparator tower 114. As best illustrated in FIG. 5, lines 116 and 118are connected to junction box 120 which are connected to a heater means122 such as resistant type heating elements. Heater means 122 are spacedin the lower compartment 124 of separating tower 114. The tower 114comprises a compartmented container being sealed by a bottom plate 146to prevent leakage into the lower compartment 124 where the heater means122 is located. Fluid from output line 282 is dumped into the upperportion of the container 124 and a baffle plate 128 allows the water toseparate from the oil mixture in the upper portion of the container.Heater means heats the mixture causing the gas to boil off which iscollected by gas outlet 130 and piped off by conduit 132. The oil issyphoned off through oil outlet line 134 which communicates with oilstorage tanks. Conduit 136 provides an emulsion down line whichcommunicates with a water drainoff valve. Hot oil will float to the topof the water. It is desirable to separate the water from the oil toprevent corrosion of the oil pipe line.

The output of several wells may be combined to flow into a singleseparator 114 and electric power generated from the output of a singlewell or multiple wells may be used to heat the emulsion to separate theemulsion into oil and gas. The separated oil and gas may be placed inseparate storage facilities and/or separate pipe lines as desired.

It should be readily apparent that any electrical device used in orabout a well site may be connected to the generator for increasing theelectrical load. Such devices may include electric clock forintermitters, electrically driven chemical pumps or any other type ofelectric device.

From the foregoing it should be readily apparent that the inventionaccomplishes the objects of the invention hereinbefore set forth.

It should also be readily apparent that other and further embodiments ofthe invention may be devised without departing from the basic conceptthereof.

Having described my invention, I claim:
 1. A process for reducingpressure of a fluid producing well by generating electricity comprisingthe steps of: directing the flow of fluid through a fluid driven motor;connecting the output shaft of the fluid driven motor to an electricalgenerator; loading the electrical generator to produce a load on themotor; controlling the load on the electrical generator to control thepressure drop across the motor.
 2. The process called for in claim 1wherein the step of loading the electrical generator comprises:attaching an electrical heating unit to the generator; and positioningthe electrical heating unit about an output pipe of the motor to heatthe fluid passing therethrough.
 3. The process of producing electricityto heat fluid passing through the pipe comprising the steps of:directing the flow of fluid through a fluid driven motor; connecting theoutput shaft of the fluid driven motor to a gear reduction transmission;connecting the gear reduction transmission to an electrical generator;connecting a heating element circuit across the output terminals of theelectrical generator; positioning the heating element about the portionof the conduit to be heated such that heat is transferred from theelectrical heating element to the pipe to heat the fluid flowingtherethrough; controlling the resistance of the heating element circuitto control the pressure drop across the fluid driven motor.
 4. Theprocess of producing electricity for separating a fluid emulsionproduced from a well comprising the steps of: directing the flow offluid through a fluid driven motor; connecting the output shaft of saidfluid driven motor through an electrical generator; connectingconductors across the output terminals of said electrical generator;connecting the conductors to a heating element circuit in a bottom of aseparation tower; deliverying the emulsion into the upper portion ofsaid tower; heating the emulsion to a predetermined temperature;collecting the gas which boils off the emulsion; syphoning off any oilfluid from the upper portion of the emulsion and draining off the waterfrom the lower portion of the emulsion; controlling the resistance ofthe heating element circuit to control the pressure drop across thefliud driven motor.
 5. Apparatus for generating electricity from thefluid pressure of a well comprising: a fluid driven motor having aninlet side and an outlet side; a well head; means securing the outlet ofsaid well head to the inlet of said fluid driven motor; an output shaftrotatably driven by said fluid driven motor; a generator; means securingsaid output shaft of said fluid driven motor to said generator; a pipeline; means securing the outlet of said fluid driven motor to the pipeline; electrical conductor means connected to the output terminals ofsaid generator load means; and means for controlling the load on thegenerator to control the pressure drop across the fluid driven motor. 6.The combination called for in claim 5 wherein said load means comprises:electric heater means secured about the outlet of said fluid drivenmotor; and connector means to connect the electric heater means to saidelectrical conductor means.
 7. The combination called for in claim 5with the addition of: an electrically driven centrifugal separatoroperably connected to said well, said separator adapted to separate thegas from the fluid produced by the well; a gas driven motor; meanscommunicating between the centrifugal separator and gas driven motor todirect the flow of gas through the gas driven motor; a second electricalgenerator for producing electricity.
 8. The combination called for inclaim 5 with the addition of: an electrically driven compressor operablyconnected to a pipe line, said electrically driven compressor adapted toincrease the pressure of fluid in a pipe line; and connector meansconnecting said electrically driven compressor to said electricalconductor means.
 9. The combination called for in claim 5 wherein saidload means comprises lights operably connected to said electricalconductor means.
 10. The combination called for in claim 5 wherein saidload means comprises: a electrically driven pump adapted to pump fluidinto said pipe line, said pump being connected to said electricalconductor means.